The invention is directed to a process for the production of 2-acetamidocinnamic acid and substituted 2-acetamidocinnamic acids. These compounds are intermediate products in the production of phenyl alanine and its derivatives.
It is known to produce 2-acetamidocinnamic acid by reaction of glycine with benzaldehyde in the presence of acetic anhydride with addition of water free (i.e., anhydrous) sodium acetate and subsequent treatment with water. The yield thereby merely amounts to about 50%. It is also kown to prepare 2-acetamidocinnamic acid in three steps by first reacting glycine with acetic acid to form acetyl glycine, converting this with benzaldehyde under addition of water free sodium acetate into 2-methyl-4-benzylidene-5-oxazolinones and finally converting this with water, in a given case with addition of acetone or sodium hydroxide into the 2-acetamidocinnamic acid. To be sure yields of about 60% are obtained thereby, but the process is expensive. In a similar manner by addition of substituted aromatic aldehydes there are formed the corresponding substituted 2-acetamidocinnamic acids, Dakin, J. Biol. Chem. Vol. 82 (1929), pages 439 to 446; Org. Synth., Col, Vol. 2 (1963) pages 1 to 3.